Hysteresis loss and storage modulus are properties of rubber that have a significant impact on tire performance. Hysteresis loss can be defined by the formula tan δ=G″/G′, where G″ is a measure of the dynamic loss modulus and G′ is the measure of storage modulus, which is indicative of hardness. Generally, as the temperature of a tire increases, G′ decreases. As a result, there may be a decrease in handling.
Inorganic fillers, such as silica, impart improved wet traction (as demonstrated by a high tan δ at 0° C.) and improved snow traction (as demonstrated by a high tan δ at −20° C.) when used as filler within tire treads. Mixing silica into a tire stock, however, is difficult because silica particles agglomerate and therefore they are not easily dispersed. In response, processing and dispersing aids are used during compounding. Unfortunately, the use of these processing and dispersing aids may enhance the decrease in modulus at high temperatures.
Because inorganic fillers are technologically useful, there is a need to overcome the problems associated with the loss of G′ at elevated temperatures in tire treads containing inorganic fillers.